Process for the manufacture of N,N-disubstituted carbamic acid halides

ABSTRACT

A process for the manufacture of N,N-disubstituted carbamic acid halides, preferably chlorides or bromides, of the general formula   IN WHICH R1 and R2 each represent an alkyl radical and R1 and R2, together with the nitrogen atom are able to form a heterocyclic ring, which optionally contains further heteroatoms, and in which X is a halogen atom, especially bromine or chlorine, wherein a secondary amine of the formula   OR THE HYDROCHLORIDE THEREOF, IS REACTED WITH A CARBONYL HALIDE IN A HIGH BOILING SOLVENT AND THE NEW N,N-disubstituted carbamic acid halides.

United States Patent [191 Somlo Mar. 11, 1975 l l PROCESS FOR THE MANUFACTURE OF N,N-DISUBSTITUTED CARBAMIC ACID HALIDES [75] Inventor: Tibor S0ml0,Birsfelden,

Switzerland [73] Assignee: Ciba-Geigy AG, Basel, Switzerland [22] Filed: Feb. 14, 1972 [21] Appl. No.: 226,320

[30] Foreign Application Priority Data Feb, 16, 1971 Switzerland 2246/71 [56] References Cited UNITED STATES PATENTS 3,320,308 5/1967 Cotin 260/544 C OTHER PUBLICATIONS Harry Tilles, J. Am. Chem. Society, Vol. 81, pages 714-727, (1959).

Primary E.\'aminerDonald G. Daus Assistant ExaminerJose Tovar Attorney, Agent, or Firm-Joseph G. Kolodny: Edward McC. Roberts; Prabodh l. Almaula 57 ABSTRACT A process for the manufacture of N.N-disubstituted carbamic acid halides, preferably chlorides or bromides, of the general formula N-CO-X in which R and R each represent an alkyl radical and R and R together with the nitrogen atom are able to form a heterocyclic ring, which optionally contains further heteroatoms, and in which X is a halogen atom, especially bromine or chlorine, wherein a secondary amine of the formula or the hydrochloride thereof, is reacted with a carbonyl halide in a high boiling solvent and the new N,N-disubstituted carbamic acid halides.

5 Claims, N0 Drawings PROCESS FOR THE MANUFACTURE OF N,N-DISUBSTITUTED CARBAMIC ACID HALIDES The present invention relates to N,N-disubstituted carbamic acid halides of the general formula wherein R and R each represent an alkyl radical and R and R together with the nitrogen atom are able to form a heterocyclic ring, which optionally contains further heteroatoms, for example oxygen, sulphur or nitrogen atoms, and wherein X is a halogen atom, preferably a chlorine or bromine atom.

The alkyl radicals R and R may contain a smaller or greater number of carbon atoms, and they may be straight-chain or branched. They may also contain aryl radicals, for example in the benzyl radical. Compounds of primary interest are those of the formula (1), in which R, and R, are alkyl radicals containing from 1 to 18 carbon atoms. Where R and R together with the nitrogen atom of the carbamic radical form a heterocyclic ring, preferred compounds are those of the formula (CH N-CO-X (2) wherein n is a positive integer from 2 to 6. Compounds of the kind characterised by the formula (2) are, for example, those in which an aziridine, pyrrolidine, piperidine or hexamethylene-imine radical is bonded to the carbamic acid halide radical. If the heterocyclic ring formed by R,, R and the nitrogen atom contains a further hetero atom in addition to the nitrogen atom, suitable compounds are primarily those of the formula nee-x wherein X, is an oxygen or sulphur atom or an NR- group, in which R is a hydrogen atom or an alkyl radical, X is a halogen atom, preferably a chlorine atom, and n and m represent positive integers which are preferably small and equal. Important compounds of this kind are those of the formula /CH CH The method generally employed is the reaction of secondary amines with phosgene according to the equation In this case, 1 mol of the amine hydrochloride is formed in addition to the desired carbamic chloride. The reaction is carried out in apolar solvents, for example benzene, at low temperatures (below 10C). The amine hydrochloride is then filtered with exclusion of atmospheric moisture and the carbamic chloride isolated from the solvent by fractionated distillation. The disadvantages of this method are that two mols of amine are required for one mol of carbamic chloride, that it is technically difficult to control the pronounced heat effect of the reaction, that the process has to be carried out at high dilutions on account of the voluminous mass of salt crystals that form, and that finally, the processing of the reactants is complicated.

Further known methods possess similar disadvantages. Thus, for example, carrying out the reaction described hereinabove with 1 mol of amine and 1 mol of pyridine instead of 2 mols of amine is expensive and complicated. And the known reaction of trimethyl amine with phosgene, which leads to the corresponding dimethylcarbamic chloride and methyl chloride, is too special; moreover, there are limits to its applicability as regards costs, since other trialkylamines, for example, triethylamine, are too expensive.

Since the manufacture of N,N-disubstituted carbamic chlorides according to the methods which are known in the art is expensive, or is complicated or linked with technical difficulties, there thus arose the need to find a method of manufacture which does not possess the disadvantages of the known methods.

The discovery has now been made that it is possible to manufacture in good yield (l00% of theory) and high purity (over N,N-disubstituted carbamic chloride of the general formula (1), if a secondary amine of the formula or the hydrochloride thereof, is reacted with phosgene in high boiling solvents, or preferably in the carbamic chloride to be manufactured itself as solvent, at elevated temperatures (at about 60-] 60C), preferably at 8095C. The amine and the phosgene are advantageously both added together simultaneously and continuously. The phosgene should be present in an excess of 5 to 10% conditioned by factors which relate to the technical apparatus used.

The reaction proceeds according to the empirical equation (R,R2)l l H2%l COCI, (R,R2)NCOCl 2 HCl so that, instead of an alkyl chloride as in the reaction mentioned hereinabove, hydrogen chloride is formed and for every mol of amine, 1 mol of the desired final product is obtained. The process may be carried out in individual batches or, preferably, continuously. In carrying out the reaction continuously, the reactants are 3 4 processed in a reaction vessel equipped with a stirrer H C and in which there is a solvent, preferably the desired 3 carbamic chloride derived from a previous batch. On N-C-Cl running in the amine and passing in phosgene the reaction proceeds of its own accord at corresponding tem- 5 perature. The resulting carbamic chloride may be drawn off from time to time in individual amounts or 400 Parts of dimethylcarbamic chloride manufactured discharged into a second vessel, from which the hydrofrom a previous batch are charged into a l /2 litre flask gen chloride which has formed and excess phosgene which is connected to a hydrogen chloride absorption are removed by passing in dry air. installation and then, while stirring at 6065C, 30 The resulting product is sufficiently pure to enable it parts of phosgene are passed in beneath the surface. to be used for most purposes without further proceSS- Then 45 parts of dimethylamine gas and 1 10-1 19 parts ng. of phosgene per hour are passed in beneath the surface As starting materials it is possible to use industrial simultaneously and uniformly. During the first half phosgene and a secondary amine, likewise of industrial h th t th dimethylamine and phosgene are passed purity. As suitable amines there may be mentioned: diin, the temperature is raised to 85C by gentle warming methylamine, diethylamine, dibutylamine, diisobutylaand then kept at 85-90C by gentle cooling. mine. y y amin d is amylamin ,diis h pty a- The dimethylcarbamic chloride which is formed can mine, py i i p p n m rp in i n y be drawn off continuously, or it is processed batchwise mine. thy y ky am heXamethylene-amine, 20 after passing in 450 parts of dimethylamine and 1100 N-methylpiperazine etc. parts of phosgene. The processing takes place by blow instead of phosgene it is possible to use other cari out the hydrogen chloride gas and excess phosgene y] halides. with dry compressed air at 6065C. In the continuous N,N-disubstituted carbamic chlorides are important variant of the process, the blowing out is carried out in commercial intermediate products for the manufacture a column filled with packing by application of the of various products. Thus, for example, by reaction counter current principle. Yield: 90-95% of theory. with alcohols, secondary amines or aromatic com- The resulting crude dimethylcarbamic chloride is pounds (according to the Friedel-Crafts reaction), it is 98-99% and can be used for most purposes; but it can possible to obtain from them the corresponding carbaalso be distilled in vacuo. Boiling point: 59C. Mimates and substituted ureas which are useful as 501- cromelting point: 34C to 35.4C. n vents and catalysts and arylcarboxylic amides. Of spe- 1.45351.4560. cial interest is their use as starting materials in the pro- If in Example 1 the 45 parts of dimethylamine are reduction of carbamates, which are valuable insecticides. placed by Substantial commercial importance therefore attaches 73 parts of diethylamine, to the improved method of manufacturing N,N-di- 35 129 parts of dibutylamine, substituted carbamic chlorides according to the present 129 parts of diisobutylamine, invention. 157 parts of diisoamylamine,

The following Examples illustrate the invention, the 213 parts of diisoheptylamine, parts and percentages being by weight unless otherwise 71 parts of pyrrolidine,

stated.

EXAMPLE 1 Dimethylcarbamic chloride parts of piperidine, 87 parts of morpholine or 197 parts of dibenzylamine, then the following carbamic chlorides are obtained:

Example Starting amine carbamic chloride boiling point Example 2 \NH b.p. :6O--62' H502 CH3CH2 3 2 2 2 cu on an on o Example 3 NH 3 2 2 2\ C 0 2 2 2 CH on CH CH /N C l Example 5 (C H NH (c n 1\ c0-01 lzl0e (Diisoamylamin) Example Starting amine carbamic chloride boiling point:

b.p. :l lO- Example 6 (0, 11 un (C H N-C0Cl 0 (diisoheptylamine i b. l- Example 7 p NH N-CO-Cl o l b p. 112

Example 8 C Q/ o Example 9 0 NH 0 N-CO-Cl -p 5 Example 10 2 2 b 0,1

/NH N-CO- Cl 152 OCH z EXAMPLE 1 l chloride passes into solution, a clear, light yellow solution bein formed. U on com letion of the introduch g P P Morp Olmocarbamlc chloride tion of phosgene, the reaction 18 stirred for half an hour 0 at 9095C and subsequently exhausted at 60 65C II with dry compressed air until it is practically free of 0 N-C-C1 phosgene. Then the chlorobenzene is distilled off at 400 Parts of morpholinocarbamic chloride are charged into a 1 V2 litre flask and at 5 to +5C 550 parts of phosgene are passed in. Then at 0 to --5C (with strong cooling) 870 parts of morpholine are added dropwise. The suspension of crystals is subsequently heated to 90C and a further 550 parts of phosgene are passed in at 90-95C. The reaction mixture is then exhausted with dry compressed air at (SO-65C until it is practically free of phosgene. In this manner there are obtained altogether 1760 parts of crude morpholinocarbamic chloride (corresponding to a yield of 91% after exhaustion ofthe initial reaction mixture). The product contains as single impurity a few percent of dimorpholinocarbamide chloride, which has no deleterious effects in most applications. The crude product can be distilled in a high vacuum; b.p. 50C; about 1500 parts of pure morpholinocarbamic chloride are obtained by distillation. n 1.4981.

EXAMPLE 12 Pyrrolidine-carbamic chloride 800 Parts of chlorobenzene are charged into a l /2 litre flask and 430 parts of pyrrolidine hydrochloride are suspended therein. The suspension of crystals is heated to 90C and 480 parts of phosgene are passed in at 90-95C within about 4 hours. Towards the end of the introduction of the phosgene the pyrrolidine hydroabout mm Hg, to leave as residue 500 g of commercially pure pyrrolidinecarbamic chloride (corresponding to a yield of 94% of theory). The product can be distilled in vacuo at b.p. 93-95C.

The pyrrolidine hydrochloride can be manufactured from pyrrolidine and hydrogen chloride gas direct in a starting flask into which chlorobenzene has been initially charged. If pyrrolidine-carbamic chloride is used as solvent instead of chlorobenzene, the separation of the chlorobenzene by distillation at the conclusion of the reaction is omitted. However, the reaction conditions and yield remain unchanged.

EXAMPLE l3 Diisopropylcarbamic chloride 400 Parts of chlorobenzene are charged into a l litre flask which is connected to a hydrogen chloride absorption installation and then, while stirring, 20 parts of phosgene are passed in at C. Then 10] parts of diisopropylamine and 55-60 parts of phosgene per hour are passed in simultaneously and uniformly. During the entire reaction the temperature is kept at 120-125C by gentle warming. After 4 hours, when altogether 404 parts of diisopropylamine and about 240 parts of phosgene have been passed in and a thick suspension of crystals has formed in the reaction flask, the flow of di isopropylamine is stopped and a further 240 parts of phosgene are introduced within 20 hours at constant temperature. The flow of phosgene must be so regulated that only hydrogen chloride gas but no phosgene escapes from the reaction flask. The reaction is complete when all the crystals have passed into solution and a clear, light yellow solution has formed. Thereupon the reaction mixture is cooled to 65C and exhausted at 60-65 with dry compressed air until it is free of phosgene. On further cooling, the diisopropylcarbamic chloride crystallises from the chlorobenzene in large rhombic crystals. It can be filtered and dried, when analytically pure diisopropylcarbamic chloride having a melting'point of 56C is obtained. Another method of processing consists in distilling off the chlorobenzene and then distilling the product in vacuo (b.p. 80C). In this process 620 g of analytically pure diisopropylcarbamic chloride having a melting point of 56C are obtained (corresponding to 95C of theory).

I claim:

1. A process for the manufacture of N,N- disubstituted carbamic acid chlorides of the formula in which R; and R each represent alkyl of l to 18 carbon atoms or benzyl, or R and R taken together with the nitrogen atom represent aziridino, pyrrolidino, piperidino, hexamethyleneimino or morpholino, consisting of the step of treating a secondary amine of the formula R R NH with phosgene, at a temperature in the range of 60 to C, wherein the solvent is the N,N-disubstituted carbamic acid chloride being manufactured.

2. The process of claim 1, wherein R and R taken together with the nitrogen atom represent aziridino, pyrrolidino, piperidino, hexamethyleneimino or morpholino.

3. The process of claim 1, wherein R, and R are benzyl or alkyl of l to 18 carbon atoms.

4. The process of claim 3, wherein R, and R are alkyl of l to 7 carbon atoms.

5. The process of claim 3, wherein R and R are benzyl. 

1. A PROCESS FOR THE MANUFACTURE OF N,N-DISUBSTITUTED CARBAMIC ACID CHLORIDES OF THE FORMULA
 1. A process for the manufacture of N,N-disubstituted carbamic acid chlorides of the formula
 2. The process of claim 1, wherein R1 and R2 taken together with the nitrogen atom represent azirIdino, pyrrolidino, piperidino, hexamethyleneimino or morpholino.
 3. The process of claim 1, wherein R1 and R2 are benzyl or alkyl of 1 to 18 carbon atoms.
 4. The process of claim 3, wherein R1 and R2 are alkyl of 1 to 7 carbon atoms. 